Polymers have previously been synthesized by the Atom Transfer Radical Polymerization (ATRP) method. The ATRP process was introduced by Matyjaszewski and Sawamoto [1-3] using different catalyst systems. ATRP is a controlled method which converts monomers to polymers by using radical polymerization. The initiators used for ATRP are commonly simple alkyl halides. A halogen atom X is transferred during the polymerization. Moreover, a catalyst system is present which consist of a transition metal complexed by one or more ligands. The catalyst provides equilibrium between the active form and the inactive form (called the dormant state). The equilibrium is displaced towards the dormant state; therefore, the polymer chains will only be active for a short time, thus allowing for a suppression of chain termination reactions and thereby controlling the polymerization. A controlled polymerization method like ATRP will result in controlled molar masses, controlled polymer architecture, and narrow molecular weight distributions (cf. schematic illustration of ATRP in FIG. 1).
PMEA coatings have previously been disclosed including PMEA-coated cardiopulmonary bypass circuits and oxygenators [4-6]. Protein adsorption studies on PMEA have also been disclosed [7-8].
PMEA polymers have previously been made by free radical polymerisation. Homopolymerization of MEA by ATRP has e.g. previously been described [9-11]. However, previously described PMEA coating is physically adsorbed to the surface whereas the PMEA made by SI ATRP such as ARGET SI ATRP or AGET SI ATRP according to the present invention is covalently bound to the surface. The covalent bonds result in a PMEA coating with improved characteristics such as improved long-term stability.